Allowing C# on Master Page and Layout Pages

1. Open web.config;
2. Find PageParserPaths node;
3. Add the following PageParserPath none so that it looks like so:
<PageParserPaths>
   <PageParserPath VirtualPath="/*" CompilationMode="Always" AllowServerSideScript="True" IncludeSubFolders="True" />
</PageParserPaths>

List of reusable SharePoint controls

Nice list of reusable SharePoint Controls:
http://community.zevenseas.com/Blogs/Robin/Lists/Posts/Post.aspx?ID=96

And more:
http://karinebosch.wordpress.com/sharepoint-controls/

SharePoint Field Controls:
http://www.hezser.de/blog/archive/2007/04/29/how-to-use-the-sharepoint-web-controls.aspx